Hot, sunny weather that is expected to break records across much of B.C. this weekend is also causing a spike in the avalanche danger rating for most regions of the province, experts are warning.
The warm temperatures in the mountains are combined with a temperature inversion that is trapping cold air in the mountain valleys and around Metro Vancouver and the South Coast, creating dense fog in many low-lying areas.
On Friday morning temperatures on top of Whistler Mountain were five degrees warmer than in the village. The alpine temperature is forecast to hit a high of 10 C on Friday and remain as high as 7 C overnight and into Saturday.
Canadian Avalanche Centre manager Karl Klassen says the snowpack is already highly unstable because of several very weak deep layers and the warm spell raises the danger for very large natural and human-triggered avalanches through the weekend.
That has prompted the centre to issue a special warning for the weekend, which applies to most regions of B.C., including North Coast Inland, South Coast Inland, Sea to Sky, North Rockies, Cariboos, North Columbia, South Columbia, Purcells, Kootenay-Boundary, Lizard Range, and South Rockies.
Klassen is also concerned about what experts call "blue sky syndrome," in which people have a false sense of security in good weather and they underestimate the hazard of avalanches.
"I think we are going to see the warm temperatures, and the strong sun triggering avalanches, and people triggering avalanches because they are not thinking of them in the beautiful weather," said Klassen.
A special warning has also been issued by Parks Canada for mountain regions in Alberta and Eastern B.C Parks Canada spokesman Omar McDadi says inexperienced people should stay out of the backcountry or only go with a professional.
"Experienced recreationalists are urged to travel on simple terrain and to stay out of the backcountry and avalanche terrain when temperatures are at their warmest."